Study on Bidirectional Blasting Technology for Composite Sandstone Roof in Gob-Side Entry-Retaining Mining Method

The traditional gob-side entry-retaining mining method has problems such as difficulty in roof collapse and large deformation of the entry, which may affect the safety of mine production. In this study, we introduced a bidirectional blasting technology (BBT) to make the roof collapse smoothly and to improve the traditional gob-side entry-retaining mining method. A theoretical model of the BBT was established and the stress propagation of the BBT was analyzed by numerical simulation. The gob-side entry-retaining mining method was then applied in a composite sandstone roof condition. Compared with ordinary blasting, the concentrated stress and directional cracks can be generated in the set direction after using the BBT technology. Field monitoring data suggested that the deformation of the retained entry met the requirements of mining, verifying the effectiveness of the proposed technology for composite sandstone roof. The results of the study have an important significance in solving the high pressure and large deformation problems in the coal mine roadway and saving coal resources, which also provided a reference for similar geotechnical mines.